The secondary structure of rabbit and human globin mRNAs is being studied by physico-chemical and biochemical means. Optical and enzymatic probes of structure are being employed. Computer predictions of structure are used to coordinate experiments and the development of structural models. Detailed secondary structure models are being developed. BIBLIOGRAPHIC REFERENCES: Specific Hydrolysis of Rabbit Globin Messenger RNA by Sl Nuclease. Flashner, M. and Vournakis, J.N. (1977) Nuc. Acid Res., in press.